Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Interaction between polycarboxylate superplasticizers and amorphous ground granulated blast furnace slag
The surface chemistry of slag dispersed in water and its behavior in cement paste were studied in the absence and presence of anionic dispersants. Three different slag samples and two polycarboxylate superplasticizers based on methacrylic acid-co-ω-methoxy poly(ethylene glycol) methacrylate ester were investigated, Electrokinetic properties of slag suspensions were determined via zeta potential measurement, revealing that initially negatively charged slag adsorbs considerable amounts of Ca2+ ions onto its surface until the point of saturation is reached. This process renders the surface of slag to be strongly positively charged in cement pore solution where a high concentration of Ca2+ ions is present. This positively charged layer of adsorbed Ca2+ ions in turn acts as an anchoring site for anionic polycarboxylate dispersants giving rise to a Langmuir - type adsorption isotherm as the dispersant adsorbs onto the surface. This study demonstrates that when blended into cement, slag is not inert with respect to these anionic superplasticizers. Instead, competitive adsorption occurs between cement and slag, which has an impact on the dosages of superplasticizers necessary to disperse CEM II / CEM III cements.
Interaction between polycarboxylate superplasticizers and amorphous ground granulated blast furnace slag
The surface chemistry of slag dispersed in water and its behavior in cement paste were studied in the absence and presence of anionic dispersants. Three different slag samples and two polycarboxylate superplasticizers based on methacrylic acid-co-ω-methoxy poly(ethylene glycol) methacrylate ester were investigated, Electrokinetic properties of slag suspensions were determined via zeta potential measurement, revealing that initially negatively charged slag adsorbs considerable amounts of Ca2+ ions onto its surface until the point of saturation is reached. This process renders the surface of slag to be strongly positively charged in cement pore solution where a high concentration of Ca2+ ions is present. This positively charged layer of adsorbed Ca2+ ions in turn acts as an anchoring site for anionic polycarboxylate dispersants giving rise to a Langmuir - type adsorption isotherm as the dispersant adsorbs onto the surface. This study demonstrates that when blended into cement, slag is not inert with respect to these anionic superplasticizers. Instead, competitive adsorption occurs between cement and slag, which has an impact on the dosages of superplasticizers necessary to disperse CEM II / CEM III cements.
Interaction between polycarboxylate superplasticizers and amorphous ground granulated blast furnace slag
Habbaba, A. (Autor:in) / Plank, J. (Autor:in)
2010
8 Seiten, 6 Bilder, 2 Tabellen, 5 Quellen
Aufsatz (Konferenz)
Englisch
Ground Granulated Blast-Furnace Slag
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